OPL wrote:
> I'm having a problem trying to read a bitmapped file into a memory stream
> and then into a byte array.
>
> Here's an example as to what I'm doing:
>
> Bitmap bmp = new Bitmap(@"c:\windows\Soap Bubbles.bmp");
> MemoryStream mem = new MemoryStream();
> bmp.Save(mem, ImageFormat.Png);
> byte[] imageArray = new byte[mem.Length];
> int nRead = mem.Read(imageArray, 0, (int)mem.Length);
>
> NB - There is no problem casting the length to an integer because we're only
> looking at image of about 60kb in size. This problem is still apparant when
> reading (, 1, 100).
>
> What happens is that the memory stream is created with the right size, and
> when the bitmap is saved the memory stream is filled with the saved byte
> array as should be (this can be verified in VS2K5 by placing the cursor over
> mem, going to "Non-public members" and looking at _buffer.
>
> For some reason I can't read the internal array from the memory stream into
> a byte array. No exception is thrown, but nRead is always 0, regardless of
> how little or how much I try to read at once.
>
> Ironically this works flawlessly when I have ImageFormat.Bmp. But I want the
> images saved as PNG because I'm going to be loading several images into
> memory.
>
> Any ideas on what the problem is or a work-around?
>
> Thanks!
>
>

"jacky kwok" <jacky.kwok@nospam.nospam> wrote in message
news:e3CKFaN7GHA.3620@TK2MSFTNGP04.phx.gbl...
> OPL wrote:
>> I'm having a problem trying to read a bitmapped file into a memory stream
>> and then into a byte array.
>>
>> Here's an example as to what I'm doing:
>>
>> Bitmap bmp = new Bitmap(@"c:\windows\Soap Bubbles.bmp");
>> MemoryStream mem = new MemoryStream();
>> bmp.Save(mem, ImageFormat.Png);
>> byte[] imageArray = new byte[mem.Length];
>> int nRead = mem.Read(imageArray, 0, (int)mem.Length);
>>
>> NB - There is no problem casting the length to an integer because we're
>> only looking at image of about 60kb in size. This problem is still
>> apparant when reading (, 1, 100).
>>
>> What happens is that the memory stream is created with the right size,
>> and when the bitmap is saved the memory stream is filled with the saved
>> byte array as should be (this can be verified in VS2K5 by placing the
>> cursor over mem, going to "Non-public members" and looking at _buffer.
>>
>> For some reason I can't read the internal array from the memory stream
>> into a byte array. No exception is thrown, but nRead is always 0,
>> regardless of how little or how much I try to read at once.
>>
>> Ironically this works flawlessly when I have ImageFormat.Bmp. But I want
>> the images saved as PNG because I'm going to be loading several images
>> into memory.
>>
>> Any ideas on what the problem is or a work-around?
>>
>> Thanks!
>
>
> You need to seek the current file position pointer in the MemoryStream mem
> to begin before read ,
>
>
> bmp.Save(mem, ImageFormat.Png);
> /*the current file pointer at the end of stream*/
>
> .....
> mem.Seek(0, SeekOrigin.Begin);
> int nRead = mem.Read(imageArray, 0, (int)mem.Length);
> ....
>
> --
> Jacky Kwok
> jacky@alumni_DOT_cuhk_DOT_edu_DOT_hk
> jacky@compose_DOT_com_DOT_hk

OPL wrote:
> Hi Jacky.
>
> Thanks heaps. That worked awesome. Any idea then why when using a Bitmap
> it's fine without needing to seek back to the beginning?
>
> Thanks.
>

> "jacky kwok" <jacky.kwok@nospam.nospam> wrote in message
> news:e3CKFaN7GHA.3620@TK2MSFTNGP04.phx.gbl...
>> OPL wrote:
>>> I'm having a problem trying to read a bitmapped file into a memory stream
>>> and then into a byte array.
>>>
>>> Here's an example as to what I'm doing:
>>>
>>> Bitmap bmp = new Bitmap(@"c:\windows\Soap Bubbles.bmp");
>>> MemoryStream mem = new MemoryStream();
>>> bmp.Save(mem, ImageFormat.Png);
>>> byte[] imageArray = new byte[mem.Length];
>>> int nRead = mem.Read(imageArray, 0, (int)mem.Length);
>>>
>>> NB - There is no problem casting the length to an integer because we're
>>> only looking at image of about 60kb in size. This problem is still
>>> apparant when reading (, 1, 100).
>>>
>>> What happens is that the memory stream is created with the right size,
>>> and when the bitmap is saved the memory stream is filled with the saved
>>> byte array as should be (this can be verified in VS2K5 by placing the
>>> cursor over mem, going to "Non-public members" and looking at _buffer.
>>>
>>> For some reason I can't read the internal array from the memory stream
>>> into a byte array. No exception is thrown, but nRead is always 0,
>>> regardless of how little or how much I try to read at once.
>>>
>>> Ironically this works flawlessly when I have ImageFormat.Bmp. But I want
>>> the images saved as PNG because I'm going to be loading several images
>>> into memory.
>>>
>>> Any ideas on what the problem is or a work-around?
>>>
>>> Thanks!
>>
>> You need to seek the current file position pointer in the MemoryStream mem
>> to begin before read ,
>>
>>
>> bmp.Save(mem, ImageFormat.Png);
>> /*the current file pointer at the end of stream*/
>>
>> .....
>> mem.Seek(0, SeekOrigin.Begin);
>> int nRead = mem.Read(imageArray, 0, (int)mem.Length);
>> ....
>>
>> --
>> Jacky Kwok
>> jacky@alumni_DOT_cuhk_DOT_edu_DOT_hk
>> jacky@compose_DOT_com_DOT_hk
>